Pick with Carbide Cap

ABSTRACT

In one aspect of the present invention, a high-impact resistant pick has a superhard material bonded to a cemented metal carbide substrate at a non-planar interface. The cemented metal carbide substrate is bonded to a front end of a cemented metal carbide bolster. A bore formed in a base end of the carbide bolster is generally opposed to the front end. A steel body has a steel shaft fitted into the bore of the bolster at an interface. A shank adapted for connection to a driving mechanism extends from the steel body opposite the shaft. A washer is disposed intermediate the base end of the carbide bolster and a shelf of the steel body.

BACKGROUND OF THE INVENTION

Formation degradation, such as asphalt milling, mining, or excavating, may result in wear on attack tools. In excavating operations, often, a trenching machine comprises an array of attack picks disposed within holders that may be rotated and moved so that the attack picks engage a hard surface. Consequently, many efforts have been made to extend the life of these tools.

U.S. Pat. No. 4,274,678 to Herridge, which is herein incorporated by reference for all that it contains, discloses a mineral mining pick boss having a socket therein for the reception of a shank of a mineral mining pick and a locking arrangement for retaining the shank, the locking arrangement comprising a plug received in the bore extending through the boss transversely of the socket the arrangement being such that the bore intersects the socket, the plug comprising a body of a resilient material (e.g. neoprene) having bonded into the periphery thereof at spaced locations a plurality of metallic members one of which protrudes from the bore into the socket for frictional engagement with the shank of the tool so as to retain the tool in position, the other(s) of the metallic members being such that the plug may be removed from the bore, rotated and re-inserted to change the metallic member which protrudes into the socket.

U.S. Pat. No. 5,873,423 to Briese, which is herein incorporated by reference for all that it contains, discloses a frustum cutting bit arrangement, including a shank portion for mounting in, and to be retained by, a rotary cutting tool body, the shank portion having an axis, an inner axial end, and an outer axial end. A head portion has an axis coincident with the shank portion axis, a front axial end, and a rear axial end, the rear end coupled to the shank portion outer end, and the front end having a conical cavity therein diminishing in diameter from the front end toward the rear end. A frustum cutting insert has an axis coincident with the head portion axis, a forward axial end, a back axial end, and an outer conical surface diminishing in diameter from the forward end toward the back end, the conical cavity in a taper lock. In variations of the basic invention, the head portion may be rotatable with respect to the shank portion, the frustum cutting insert may comprise a rotating cutter therein, and combinations of such features may be provided for different applications.

U.S. Pat. No. 5,702,160 to Levankovskii et al., which is herein incorporated by reference for all that it contains discloses a tool for crushing hard material comprising a housing and a hard-alloy insert mounted on the latter. The insert is made up of a head portion, an intermediate portion and a base with a thrust face. The intermediate portion of the insert is formed by a body of revolution with an outer lateral surface of concave shape. The head portion of the insert is formed by a body of revolution with an outer lateral surface of convex shape. The lateral side of the head portion of the insert is smoothly located adjacent to the lateral side of the intermediate portion of the insert about its longitudinal axis does not exceed the length of the head portion of the insert about the same axis.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a high-impact resistant pick has a superhard material bonded to a cemented metal carbide substrate at a non-planar interface. The cemented metal carbide substrate is bonded to a front end of a cemented metal carbide bolster. A bore formed in a base end of the carbide bolster is generally opposed to the front end. A steel body has a steel shaft fitted into the bore of the bolster at an interface. The bore may be tapered. A shank adapted for connection to a driving mechanism extends from the steel body opposite the shaft. A washer is disposed intermediate the base end of the carbide bolster and a shelf of the steel body. The pick may be adapted for attachment to a trenching machine, mining machine, pavement milling machine, or a combination thereof.

The washer may be brazed intermediate the carbide bolster and the shelf of the steel body and may be adapted to rotate independent of the carbide bolster and the steel body. The washer may also have a wear-resistant coating. The carbide bolster and the shelf of the steel body may be adapted to compress the washer and thereby prohibit rotation of the washer. The washer and the body may comprise a tool steel. More specifically, the washer and the base may comprise S7 tool steel. A second washer may be disposed adjacent a base end of the shelf of the steel body.

A portion of the steel shaft adjacent the bore of the bolster may have a concave geometry. The shank may be held within a holder of the driving mechanism and may be lubricated. The interface of the shaft may compliant, thereby extending the life of the pick. The steel shaft may be press-fit into the bore of the carbide bolster, the press-fit having an interference of 0.0005 to 0.0020 inch. The bore of the carbide bolster may have a depth of 0.50 to 3 inches. The carbide substrate may have a thickness of 0.050 to 1.0 inch. In some embodiments the carbide substrate may have a thickness of 0.050 to 0.300 inch. The carbide substrate and carbide bolster may be brazed with a braze material comprising 30 to 62 weight percent of palladium.

The superhard material may have a substantially pointed geometry with an apex having a 0.050 to 0.160 inch radius, and a 0.100 to 0.500 inch thickness from the apex to the non-planar interface. The superhard material may be a material selected from the group consisting of diamond, monocrystalline diamond, polycrystalline diamond, sintered diamond, chemical deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, layered diamond, thermally stable diamond, silicon-bonded diamond, metal-bonded diamond, and combinations thereof.

In another aspect of the present invention, a high-impact resistant pick has a superhard material bonded to a cemented metal carbide substrate at a non-planar interface. The cemented metal carbide substrate is bonded to a front end of a cemented metal carbide bolster. A bore formed in a base end of the carbide bolster is generally opposed to the front end. A steel body has a steel shaft fitted into the bore of the bolster at an interface. The bore may be tapered. A shank adapted for connection to a driving mechanism extends from the steel body opposite the shaft. The base end of the carbide bolster is in contact with a shelf formed in the steel body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram of an embodiment of a plurality of picks on a rotating chain attached to a motor vehicle.

FIG. 2 is an exploded diagram of an embodiment of a pick.

FIG. 3 is a cross-sectional diagram of an embodiment of a degradation assembly.

FIG. 3 a is a cross-sectional diagram of another embodiment of a pick.

FIG. 4 is a cross-sectional diagram of another embodiment of a degradation assembly.

FIG. 5 is a cross-sectional diagram of another embodiment of a pick.

FIG. 6 is a cross-sectional diagram of another embodiment of a pick.

FIG. 7 is a cross-sectional diagram of another embodiment of a pick.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

FIG. 1 illustrates a plurality of picks 101 on a rotating chain 102 attached to a motor vehicle 103, specifically, a trenching machine. In other embodiments, the picks may be adapted for attachment to a mining machine, pavement milling machine, or a combination thereof. The plurality of picks 101 may be exteriorly mounted in a “V” pattern on the chain 102 to facilitate degradation and removal of a formation 104. The rotating chain 102 rotates in a direction indicated by an arrow 150 and cuts the formation 104 forming a trench while bringing the formation cuttings out of the trench to a conveyor belt 105 which directs the cuttings to a side of the trench. The rotating chain 102 is supported by an arm 107. The arm 107 may be raised while the machine is being transported or it may be lowered for trenching as shown in FIG. 1. The position of the arm may be controlled by a hydraulic piston and cylinder 108. The trenching machine may move about the formation 104 by tracks 109, wheels, or a combination thereof A seat 106 for an operator is positioned on the side of the machine.

FIG. 2 is an exploded diagram of an embodiment of a pick 101. In the preferred embodiment, the pick 101 has a superhard material 200 bonded to a cemented metal carbide substrate 201 at a non-planar interface. The superhard material may be a material selected from the group consisting of diamond, monocrystalline diamond, polycrystalline diamond, sintered diamond, chemical deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, layered diamond, thermally stable diamond, silicon-bonded diamond, metal-bonded diamond, and combinations thereof. The substrate 201 may comprise a thickness 230 of 0.050 to 1.0 inch. In the preferred embodiment, the substrate 201 comprises a thickness 230 of 0.050 to 0.300 inch. It has been discovered that incorporating a thin substrate into the pick may increase the life of the pick. The cemented metal carbide substrate 201 may also be bonded to a front end 202 of a cemented metal carbide bolster 203. In this embodiment, the substrate 201 may be brazed to the bolster 203 with a braze material 250 comprising 30 to 62 weight percent of palladium. A bore 204 formed in a base end 205 of the carbide bolster 203 generally opposed to the front end 202. A steel body 206 having a steel shaft 207 may be fitted into the bore 204 of the bolster 203 at an interface 208. The bore 204 may be tapered. The steel shaft 207 may be press-fit into the bore 204 of the carbide bolster 203, the press-fit having an interference of 0.0005 to 0.0020 inch. This implies that the bore 204 of the carbide bolster 203 has a diameter 260 smaller than a diameter 261 of the steel shaft 207. The bore 204 may comprise a depth 262 of 0.40 to 3 inches. A shank 209 adapted for connection to a driving mechanism extends from the steel body 206 opposite the shaft 207. A washer 210 may be disposed intermediate the base end 205 of the carbide bolster 203 and a shelf 211 of the steel body 206. The washer 210 and/or the body 206 may comprise a tool steel.

Referring now to FIG. 3, an embodiment of a degradation assembly 300 may comprise a holder 301, a chain 102, and a pick 101; the holder 301 being attached directly to the rotating chain 102 supported by the arm 107 of the trenching machine. In the preferred embodiment, the holder 301 may be welded to the chain 102. In other embodiments, the holder may be bolted to the chain. The shank 209 of the steel body 206 may be fitted into the holder 301. In this embodiment, the shank 209 may be press-fit into the holder. The washer 210 may be disposed between the shelf 211 of the steel body 206 and the carbide bolster 203. In this embodiment, the washer 210 may be compressed by the bolster 203 and the shelf 211, thereby prohibiting rotation of the washer 210. In other embodiments, the washer may be brazed to the carbide bolster and the shelf of the steel body. A second washer 350 may be disposed intermediate a base end 302 of the shelf 211 of the steel body 206 and the holder 301. The second washer 350 may help to reduce wear on the pick during an operation. It is believed that it may be easier and cheaper to replace the second washer rather than replacing the holder 301. In this embodiment, the steel shaft 207 may be press-fit into the carbide bolster 203 at an interface 208. The interface 208 of the shaft 207 may be compliant. It has been found that incorporating a gap 303 between the interface 208 and the carbide bolster 203 may allow for more compliance of the steel shaft 207 during an operation thereby prolonging the life of the pick.

A superhard material 200 may be bonded to a cemented metal carbide substrate 201 at a non-planar interface 304. As illustrated in this figure, a tip 305 of the superhard material 200 may contact the formation 104, causing cracks 306 to form in the formation 104 and thereby breaking up the formation 104.

Now referring to FIG. 3 a, a pick 101 may comprise a superhard material 200 bonded to a carbide substrate 201 at a non-planar interface 304. A wall 360 and a central axis 361 of the superhard material 200 may generally form a 35 to 45 degree included angle 362. The wall may be at an angle 362 such that if the generally flat portion of the wall 360 is extended, illustrated by a line 363. In the preferred embodiment, the carbide substrate 201, pick body 206, carbide bolster 203, washer 210, and other portions of the pick 101 do not extend beyond the line 363. This may be beneficial in that during a degradation operation the point of contact between the pick 101 and a formation occurs at the tip 305 of the superhard material 200 rather than other portions of the pick 101, thereby prolonging the wear-life of the pick 101. The base of the carbide bolster is also shown contacting the shelf formed in the steel body.

A degradation assembly 300 shown in FIG. 4 comprises a shank 209 of the pick 101 held within a holder 301; the shank being lubricated. A lubricant reservoir 400 containing fluid may be disposed within the holder 301 adjacent a proximal end 401 of the pick 101. The lubricant reservoir 400 may supply lubricant to the shank 209 assisting the rotatability of the pick 101 by reducing friction. A seal assembly 450 proximate the opening of a central bore 406 and disposed intermediate the pick 101 and the holder 301 may comprise an o-ring 451 partially disposed in a reentrant proximate a junction of the shank 209 and the body 206. The lubricant reservoir 400 may also comprise a plunger 452 and a spring 453 to apply continual pressure on the lubricant. A filling port 402 adjacent to the lubricant reservoir 400 enables outside access to the lubricant reservoir 400 such that additional lubricant may be added to the lubricant reservoir.

The shank 209 may have a reduced diameter portion 403 disposed intermediate the steel body 206 and the proximal end 401 of the shank 209. A tensioning mechanism 404 comprising a radially expandable spring 405 may be disposed around the reduced diameter portion 403 such that it may not slideably move along the length of the shank 209 beyond the reduced diameter portion 403. The outermost diameter of the spring 405 may be larger than the diameter of the shank 209. The spring 405 may have a diameter less than or equal to the diameter of the shank 209 when the spring is compressed. The pick 101 may be connected to the holder 301 by placing the shank 209 into the central bore 406; the spring 405 may be compressed as it passes the opening of the bore 406. As the shank 209 reaches a tapered portion 407 of the bore 406 the spring 405 expands in diameter and pulls the pick 101 downward against the holder 301. The reduced diameter portion 403 of the shank 209 and the spring 405 never reach an expanded diameter portion 408 of the bore 406 yet remain in the tapered portion 407 of the bore 406. Because the spring 405 may be adapted to expand in diameter as the bore 406 diameter increases, the spring 405 may continue to induce an axial tensional force in the shank 209 so long as the spring 405 remains in the tapered portion 407 of the bore 406. The axial tensional force in the shank 209 maintains the connection of the pick 101 to the holder 301. The pick 101 may be rotatable while connected to the holder 301.

A second washer 350 may be disposed intermediate the pick body 206 and the holder 301. The holder 301 may have a knurled interface 409 that engages the second washer 350 preventing the second washer 350 from rotating about a central axis 410 without inhibiting the rotatability of the pick 101. In some embodiments, the tension exerted on the pick is sufficient enough to substantially rotationally fix the second washer against the holder, even without knurling, while still allowing the pick to rotate.

FIGS. 5 through 7 illustrate various embodiments of a pick 101. In the embodiment of FIG. 5, the pick 101 may comprise a washer 210 disposed intermediate the base end 205 of the carbide bolster 203 and the shelf 211 of the steel body 206. In this embodiment, the washer 210 is not compressed between the base end 205 and the shelf 211, thus the washer 210 may be adapted to rotate independent of the carbide bolster 203 and the steel body 206. The washer 210 may comprise a wear-resistant coating. The carbide bolster 203 may comprise a segmented geometry 500. Also in this embodiment, the shaft 207 of the steel body 206 may comprise a flat, tapered portion 501. The interface 208 of the shaft 207 may be compliant in that the interface 208 may comprise a gap 303 intermediate the carbide bolster 203 and the steel shaft 207; the gap 303 forming a concavity 502 within the shaft 207. A second washer 350 may be disposed adjacent a base end 302 of the shelf 211 of the steel body 206.

Referring now to FIG. 6, the interface 208 comprises a plurality of slits 600 formed in the steel shaft 207. In this embodiment, the washer 210 may comprise a stepped geometry 601. The stepped geometry 601 may be beneficial in lowering the cost of the pick assembly by reducing the amount of carbide used in the bolster. A portion of the steel body 206 may comprise a hardfacing material 602. In some embodiments, the outer surface of the washer 210 may also comprise the hardfacing material 602. The bolster 203 of the pick 101 may comprise an overhang 603 such that the outer surface of the bolster 203 may align with the hardfacing material 602. In this embodiment, the bolster 203 may comprise a flat geometry 604.

FIG. 7 illustrates a pick 101 having a carbide bolster 203 comprising a convex geometry 700. A portion 701 of the steel shaft 207 adjacent the bore 204 of the bolster 203 comprises a concave geometry. The washer 210 may be tapered such that a lesser amount of carbide is required for the carbide bolster 203. A hardfacing material 602 may be disposed about a portion of the steel body 206. The washer 210 may comprise an overhang 702 so that the outer surface of the washer and the hardfacing material 602 align. The superhard material 200 may comprise a substantially pointed geometry with an apex 703 comprising a 0.050 to 0.160 inch radius, and a 0.100 to 0.500 inch thickness from the apex 703 to the non-planar interface 304.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention. 

1. A high-impact resistant pick, comprising: a superhard material bonded to a cemented metal carbide substrate at a non-planar interface; the cemented metal carbide substrate being bonded to a front end of a cemented metal carbide bolster; a bore formed in a base end of the carbide bolster generally opposed to the front end; a steel body comprising a steel shaft being fitted into the bore of the bolster at an interface; a shank adapted for connection to a driving mechanism extends from the steel body opposite the shaft; and a washer disposed intermediate the base end of the carbide bolster and a shelf of the steel body.
 2. The pick of claim 1, wherein the washer is brazed intermediate the carbide bolster and the shelf of the steel body.
 3. The pick of claim 1, wherein the washer is adapted to rotate independent of the carbide bolster and the steel body.
 4. The pick of claim 3, wherein the washer comprises a wear-resistant coating.
 5. The pick of claim 1, wherein the carbide bolster and the shelf of the steel body are adapted to compress the washer and thereby prohibit rotation of the washer.
 6. The pick of claim 1, wherein the bore is tapered.
 7. The pick of claim 1, wherein a second washer is disposed adjacent a base end of the shelf of the steel body.
 8. The pick of claim 1, wherein a portion of the steel shaft adjacent the bore of the bolster comprises a concave geometry.
 9. The pick of claim 1, wherein the shank is held within a holder of the driving mechanism and is lubricated.
 10. The pick of claim 1, wherein the washer comprises a tool steel.
 11. The pick of claim 1, wherein the body comprises a tool steel.
 12. The pick of claim 1, wherein the interface of the shaft is compliant.
 13. The pick of claim 1, wherein the steel shaft is press-fit into the bore of the carbide bolster, the press-fit comprising an interference of 0.0005 to 0.0020 inch.
 14. The pick of claim 1, wherein the bore of the carbide bolster comprises a depth of 0.50 to 3 inches.
 15. The pick of claim 1, wherein the carbide substrate comprises a thickness of 0.050 to 1.0 inch.
 16. The pick of claim 16, wherein the carbide substrate comprises a thickness of 0.050 to 0.300 inch.
 17. The pick of claim 1, wherein the carbide substrate and carbide bolster are brazed with a braze material comprising 30 to 62 weight percent of palladium.
 18. The pick of claim 1, wherein the superhard material comprises a substantially pointed geometry with an apex comprising a 0.050 to 0.160 inch radius, and a 0.100 to 0.500 inch thickness from the apex to the non-planar interface.
 19. The pick of claim 1, wherein the superhard material is a material selected from the group consisting of diamond, monocrystalline diamond, polycrystalline diamond, sintered diamond, chemical deposited diamond, physically deposited diamond, natural diamond, infiltrated diamond, layered diamond, thermally stable diamond, silicon-bonded diamond, metal-bonded diamond, and combinations thereof.
 20. A high-impact resistant pick, comprising: a superhard material bonded to a cemented metal carbide substrate at a non-planar interface; the cemented metal carbide substrate being bonded to a front end of a cemented metal carbide bolster; a bore formed in a base end of the carbide bolster generally opposed to the front end; a steel body comprising a steel shaft being fitted into the bore of the bolster at an interface; a shank adapted for connection to a driving mechanism extends from the steel body opposite the shaft; and the base end of the carbide bolster being in contact with a formed in a shelf of the steel body. 